TransactionSynchronization implementations can implement the Ordered interface
to influence their execution order. A synchronization that does not implement the
Ordered interface is appended to the end of the synchronization chain.

System synchronizations performed by Spring itself use specific order values,
allowing for fine-grained interaction with their execution order (if necessary).

beforeCommit

This callback does not mean that the transaction will actually be committed.
A rollback decision can still occur after this method has been called. This callback
is rather meant to perform work that's only relevant if a commit still has a chance
to happen, such as flushing SQL statements to the database.

Note that exceptions will get propagated to the commit caller and cause a
rollback of the transaction.

Parameters:

readOnly - whether the transaction is defined as read-only transaction

Throws:

RuntimeException - in case of errors; will be propagated to the caller
(note: do not throw TransactionException subclasses here!)

afterCommit

Invoked after transaction commit. Can perform further operations right
after the main transaction has successfully committed.

Can e.g. commit further operations that are supposed to follow on a successful
commit of the main transaction, like confirmation messages or emails.

NOTE: The transaction will have been committed already, but the
transactional resources might still be active and accessible. As a consequence,
any data access code triggered at this point will still "participate" in the
original transaction, allowing to perform some cleanup (with no commit following
anymore!), unless it explicitly declares that it needs to run in a separate
transaction. Hence: Use PROPAGATION_REQUIRES_NEW for any
transactional operation that is called from here.

Throws:

RuntimeException - in case of errors; will be propagated to the caller
(note: do not throw TransactionException subclasses here!)

afterCompletion

NOTE: The transaction will have been committed or rolled back already,
but the transactional resources might still be active and accessible. As a
consequence, any data access code triggered at this point will still "participate"
in the original transaction, allowing to perform some cleanup (with no commit
following anymore!), unless it explicitly declares that it needs to run in a
separate transaction. Hence: Use PROPAGATION_REQUIRES_NEW
for any transactional operation that is called from here.

Parameters:

status - completion status according to the STATUS_* constants

Throws:

RuntimeException - in case of errors; will be logged but not propagated
(note: do not throw TransactionException subclasses here!)